1. Field of the Invention
The present invention relates generally to evaluation and verifier systems. More particularly, the invention relates to methods and apparatus to enable the face of a data carrying graphical symbol, such as a 1D or 2D bar code, to be scanned in a controlled and desired manner to generate a plurality of preferably equi-spaced scans that are taken along at least a portion of the respective height of the face of the graphical symbol.
2. Description of the Prior Art
The scanning of bar code indicia with devices such as laser scanners, hand-held wands, and the like, results in a single scan being taken. Each scan taken may be assumed to generate a scan reflectance profile (SRP) signal, which is associated with the scanned location or region of the indicia. Often the SRP signal is digitized, generally in real-time (as the SRP signal is generated), to produce a sequence of digital samples that may be stored in a suitable memory structure. Most typically, all the samples produced are stored in an available memory and are later analyzed to determine the quality of the scanned indicia. Alternately, as taught by U.S. Pat. No. 5,633,488 to Spitz, the samples may be pre-processed to `filter` and essentially store only samples that are required to quantitatively evaluate the scanned indicia.
At present, a number of industry standards or guidelines exist that establish acceptable methods that may be employed to quantitatively evaluate the quality of bar code indicia. Two such guidelines, which are well known in the art, have been established by the American National Standards Institute (ANSI), and the Uniform Code Council (UCC). The ANSI guideline (ANSI X3.182-1990) is titled "Bar Code Print Quality Guideline". The UCC guideline is titled "Quality Specification for the UPC Printed Symbol" (September 1994). These guidelines are concerned with the scanning and quantitative evaluation of 1-dimensional bar code indicia. An important requirement that should be met to provide true `ANSI level reporting` of the quality of an indicia is the generation of a plurality of spaced scans taken along the height of the indicia being evaluated (see FIG. 4). This succession of scans may be described as being `taken at equally spaced locations within an interrogation window` along the height of the elements forming the bar code indicia.
The generation of a plurality of equi-spaced scans is relatively easy when the indicia (or equivalently a suitable `graphical symbol`) to be evaluated is disposed on a moving substrate that is moving past the scanner at a substantially constant rate. For example, if the respective indicia to be evaluated are being printed on a substrate that is passing through a printing device, a scanner may be mounted in a suitable location to scan the indicia as they exit or pass through the printing device. These types of evaluation systems are termed `on-line` as they may be configured to scan each and every indicia printed, often in real-time. It may be noted that on-line, possibly real-time ANSI reporting evaluation systems are typically prohibitively expensive to many organizations that would like to provide verification as indicia are printed.
An alternate approach, which provides a reasonable level of verification, is to employ self-contained devices that include hand-held scanning devices. For example, there are known devices that employ hand-held laser scanners and wands. However, when considering the scanning of a single stationary indicia, the generation of the plurality of spaced scans, especially equally spaced somewhat rapidly taken scans, is difficult, if not impossible. An operator's skill and patience can be determining factors in the success and results of such an evaluation. Further, if it is desired to scan a complex data carrying indicia, such as a 2-dimensional or matrix-type bar code indicia, these simple prior art devices are inadequate for the task. When considering the need to scan such 2D bar code indicia, specialized scanning engines, which are commonly referred to as `raster scanning engines`, are known in the art. However, raster scanning devices are generally structured to provide accurate reading and decoding of the content or information contained in a 1D or 2D indicia. As such, they are not configured to maintain a constant or nearly constant distance between the scanned symbol and scanning device's source/receiver portion. For very accurate and consistent evaluation of graphical symbol along the height thereof, maintaining a constant distance, and possibly a constant angle, between the scanner unit and scanned symbol may be most desirable.
Therefore, there is a need to provide new and improved methods and means to scan a stationary data carrying graphical symbol to provide a plurality of preferably equi-spaced scans (each yielding an SRP signal) having one or more of the following capabilities, features, characteristics, and or advantages:
a movably mounted scanner unit that may be positioned in any one of a plurality of scanning positions to cause scans of an indicia to be taken along at least a portion of the height of elements composing the scanned indicia; PA1 a drive unit employable to position the movable scanner unit in a desired/required position; PA1 maintain a constant scan distance between a face of a scanned data carrying graphical symbol and a scanning unit, as the scanning unit is moved in a controlled manner to enable the plurality of scans to be collected; PA1 a support structure such as a support bed, or equivalent means, to support a substrate having a data carrying graphical symbol disposed (e.g., printed) thereon; PA1 embodiments wherein the scanner unit is housed below the data carrying graphical symbol and scans upwardly onto elements thereof; PA1 embodiments wherein the scanner unit is positioned above the graphical symbol and scan down onto elements; PA1 may include at least one transparent (e.g., plastic or glass) plate and or an opaque plate to support or hold a substrate having disposed thereupon a graphical symbol to be scanned; PA1 simple construction to provide a cost effective scanning and evaluation arrangement; and PA1 economical construction, possibly employing a number of off-the-shelf components.
The above listed capabilities, characteristics, and or associated novel features of the present invention, as well as others, may become more clear from a careful review of the description and figures provided herein. Attention is called to the fact, however, that the drawings and descriptions are illustrative only. Variations are contemplated as being part of the invention, limited only by the scope of the appended claims.